Volvo Penta TMD40A oil alarm and expansion tank

[179580]

That does not seem to agree with the parts diagram which lists the cap on the expansion tank as a pressure cap and the cap on the top part of the thermostat housing as just a plain filler cap,.
The angled pipe does not appear to come from the filler cap neck so is not the overflow associated with a pressure cap.
Its unclear where the hose from the bottom of the expansion tank goes but presumably somewhere around the heat exchanger / thermostat housing which will be pressurised

I would expect the little vent pipe on the expansion tank to be sealed or for a pressure cap which seats at the bottom of the neck to be fitted

Note item 39, the tube that screws in the expansion tank. It is quite long extending to almost the bottom of the tank. When the engine cools it will keep water in the header. Note that the parts diagram shows the pipe in the lower position but the op is in the upper position.

 

[dragoon]

Congratulations on your purchase of Storebro. We have a 34' Baltic from the same year.

We have the TAMD40B engines, which have a different cooler, so I can't help on the question there.

On the oil switch, that looks like the alarm switch to me. The pressure switch has screwed terminals. The replacement switch has a different plug on top and you need to buy an adapter cable with it.

 

[VicS]

Interesting. I did suggest that the B lugs were vented to atmosphere but I've never seen a pressure relief valve and a vacuum release valve combined into one fitting like that.

It's a clever construction which, if the little plastic tube has indeed been opened out into the expansion tank air space, is totally wasted.

I might be tempted to block off the plastic tube and see what happens.

Richard

All the ones I hve seen have the vac release valve and the pressure control valve combined into one ....
Here,s a manky old conventional one with the vac release valve being held open

 

[RichardS]

All the ones I hve seen have the vac release valve and the pressure control valve combined into one ....
Here,s a manky old conventional one with the vac release valve being held open

View attachment 115244

Errrrr ..... that's a standard pressure/vacuum two way cap which I have seen hundreds of. However that is clearly two valves ..... the pressure relief valve uses the external visible spring and central rubber seal and the vacuum release uses a hidden internal spring and probably a hidden internal seal. When the cap is under pressure the central rubber seal is pushed upwards to allow fluid to flow into the expansion vessel.

The cap you posted a picture of in #19 does not appear to have a moving central sprung part and certainly no central seal therefore both pressure and vacuum relief seals and springs must be combined into one fitting, unless it's just the angle that the photo is taken from and the spring is hidden in the dark area.

Richard

 

[VicS]

The cap you posted a picture of in #19 does not appear to have a moving central sprung part and certainly no central seal therefore both pressure and vacuum relief seals and springs must be combined into one fitting, unless it's just the angle that the photo is taken from and the spring is hidden in the dark area.

Richard

Yes it does it's the little disc, about 4 or 5 mm diameter, which I labelled "A". It is possible to lift it against its spring in the same way as I'm showing with the other one in # 23.
The heavier spring for the pressure valve is inside the brass part. It is not visible, nothing to do with the angle of the photograph. .
The brass part, complete with both valves and their springs can be removed from the cap itself.

 

[RichardS]

Yes it does it's the little disc, about 4 or 5 mm diameter, which I labelled "A". It is possible to lift it against its spring in the same way as I'm showing with the other one in # 23.
The heavier spring for the pressure valve is inside the brass part. It is not visible, nothing to do with the angle of the photograph. .

So the exterior brass part is not movable and both the moving valves, both the springs and both the seals are combined internally into one fitting, which is totally unlike a normal pressure/vacuum cap, exactly as I said.

Richard

 

[VicS]

So the exterior brass part is not movable and both the moving valves, both the springs and both the seals are combined internally into one fitting, which is totally unlike a normal pressure/vacuum cap, exactly as I said.

Richard

There are three main components. The plastics cap, the brass capsule containing the valves and their springs and a rubber sealing washer
The valves are pretty much the same in principle as in the conventional caps ie a sprung pressure valve with the vacuum release valve in its centre.
The brass capsule, iirc, has a flange at the top which seals, via the rubber washer, onto the top of the expansion vessel neck

 

[RichardS]

There are three main components. The plastics cap, the brass capsule containing the valves and their springs and a rubber sealing washer
The valves are pretty much the same in principle as in the conventional caps ie a sprung pressure valve with the vacuum release valve in its centre.
The brass capsule, iirc, has a flange at the top which seals, via the rubber washer, onto the top of the expansion vessel neck

Of course the actual valve mechanisms are the same in the standard construction cap as it is with your cap. I have never suggested anything to the contrary.

What is very different to usual is that in your cap both the valves are contained in a single encapsulated fitting ...... exactly as I said.

Let's put it this way, I have seen literally hundreds of pressure/vacuum caps like the one in your post #23 during the last 55 years. I have never seen a single one in the flesh which is like the one you posted in your post #19. My ratio of conventional design to Volvo design is therefore, say 500:0.

What would you say your ratio is?

Richard

 

[Nunuwawa]

I might be tempted to block off the plastic tube and see what happens.

This is what I am going to try.

Regarding the overheating engine
any suggestions how to start troubleshooting?
The raw water pump is overhauled and the exhaust pipe elbow renewed,
exhaust pipe elbow stays cool while running so the problems seems to be in the intern cool system.
I started the engine and the temperature came fast to 90 C
when I stopped the engine a lot of cooling water was pushed out....................................

Thanks

Walter

 

[RichardS]

This is what I am going to try.

Regarding the overheating engine
any suggestions how to start troubleshooting?
The raw water pump is overhauled and the exhaust pipe elbow renewed,
exhaust pipe elbow stays cool while running so the problems seems to be in the intern cool system.
I started the engine and the temperature came fast to 90 C
when I stopped the engine a lot of cooling water was pushed out....................................

Thanks

Walter

If that top plastic tube is open to the air space at the top of the expansion vessel then I would assume that the coolant system must be running at atmospheric pressure. This will inevitably lead to loss of coolant, one way or another, and overheating.

Do both engines have that upper plastic tube drilled through?

Richard

 

[dragoon]

If you suspect the internal cooling system you could take one (or both of the thermostats out).

Also, do you see water circulating in the top of the exchanger when the engine is running?

My experience of these engines (TAMD40s) is that the oil cooler blocks and causes a raw water restriction.

 

[dragoon]

This is what I am going to try.

Regarding the overheating engine
any suggestions how to start troubleshooting?
The raw water pump is overhauled and the exhaust pipe elbow renewed,
exhaust pipe elbow stays cool while running so the problems seems to be in the intern cool system.
I started the engine and the temperature came fast to 90 C
when I stopped the engine a lot of cooling water was pushed out....................................

Thanks

Walter

Also, is getting to 90C whilst underway or at the dock? I've run mine up at fast idle with the cap off before and not even got the engines that warm, so just curious.

 

[VicS]

Regarding the overheating engine. any suggestions how to start troubleshooting?
The raw water pump is overhauled and the exhaust pipe elbow renewed,
exhaust pipe elbow stays cool while running so the problems seems to be in the intern cool system.
I started the engine and the temperature came fast to 90 C
when I stopped the engine a lot of cooling water was pushed out....................................

Thanks
Walter

I was also going to suggest checking the thermostats ... one should start to open at 70C and the other at 76C .... Its unlikely that both will have failed, possible though.

Maybe you ought to look at the coolant pump ????

 

[Leighb]

If the temperature rises quickly to 90C when either on the dock or just at low rpm there is definitely something wrong, failure of the priming on the raw water pump is common, and I have experienced this, in my case the temp rose quickly, 5 to 10 mins to 90+. If it is only under load, which I have also had as a recurring problem, then there is probably some restriction in the cooling system. The raw water flows from the pump via the strainer to the oil cooler, then to the gearbox oil cooler and finally to the heat exchanger. It is then ejected via the injection bend into the exhaust.
There are many places where the system can get blocked up with crud and only by stripping it all down can you be sure that all has been cleared.
Re the sender, there is an alarm on the panel with all instruments as well as the one on the flybridge. On mine there are two senders, one for the alarm the other for the gauge. One has two terminals, the other only one.

 

[dragoon]

I was also going to suggest checking the thermostats ... one should start to open at 70C and the other at 76C .... Its unlikely that both will have failed, possible though.

Maybe you ought to look at the coolant pump ????

BTW the sensor you asked about originally is definitely a pressure sensor , not a temperature sensor, and is, I think, the sensor for the low oil pressure warning light and alarm on a fly-bridge control panel, which does not have oil pressure or coolant temperature gauges

It definitely looks looks like the low oil pressure warning switch as you say. If his Storebro is set up the same as mine, it will have alarms at the helm station, but no light. I added lights to mine as a visual warning. The old part is no longer available and is replaced by 863169 and a wiring harness conversion 873601. They are seen here - I had to add a new one to mine at some point. TAMD40B - Diesel Engine

 

[VicS]

If the temperature rises quickly to 90C when either on the dock or just at low rpm there is definitely something wrong, failure of the priming on the raw water pump is common, and I have experienced this, in my case the temp rose quickly, 5 to 10 mins to 90+. If it is only under load, which I have also had as a recurring problem, then there is probably some restriction in the cooling system. The raw water flows from the pump via the strainer to the oil cooler, then to the gearbox oil cooler and finally to the heat exchanger. It is then ejected via the injection bend into the exhaust.
There are many places where the system can get blocked up with crud and only by stripping it all down can you be sure that all has been cleared.
Re the sender, there is an alarm on the panel with all instruments as well as the one on the flybridge. On mine there are two senders, one for the alarm the other for the gauge. One has two terminals, the other only one.

The OP says that the exhaust elbow remains cool. This indicates a good cooing water flow water surely?

 

[dragoon]

The OP says that the exhaust elbow remains cool. This indicates a good cooing water flow water surely?

(re the sensor.. The wiring diagram shows a combined oil pressure gauge sender and alarm sensor for the main panel, with two terminals and an earth return, and a separate sensor for the fly bridge panel. I am pretty sure the sensor in question is the one for the flybridge panel which is shown with two terminals, although one is in fact earthed)

The gauge sender and alarm are not combined, but live on a common t-piece just in front of the oil cooler. The pressure send is part 866833 and has 2 knurled knobs on it. The genuine alarm sender should have 2 connections (although Leighb reports 1) as it's not supposed to earth via the switch.

 

[VicS]

The gauge sender and alarm are not combined, but live on a common t-piece just in front of the oil cooler. The pressure send is part 866833 and has 2 knurled knobs on it. The genuine alarm sender should have 2 connections (although Leighb reports 1) as it's not supposed to earth via the switch.

Yes you are right. Pervious comments deleted.
One terminal of the sensor is earthed though. It has to be to complete the circuit back to battery negative

 

[179580]

Only one way to go, completely strip the cooling system, clean and look for blockages. Do not forget, rubber hoses can de-laminate from the inside and create "bubbles" in the hose causing restrictions.

 

[dragoon]

Yes you are right. Pervious comments deleted.
One terminal of the sensor is earthed though. It has to be to complete the circuit back to battery negative

Correct, on the VP part the connection that goes to earth is connected to a bolt on the oil cooler to make the circuit.